Radio compass loop construction



. y 1941. F. D. HERBERT, JR 2,251,131

RADIO COMPASS LOOP CONSTRUCTION Filed Aug. 24, A939 l N V E N T O R f-Tefof/P/ck Q #52552 7e.

ATTORNEY Patented July 29, 1941 gag-fa RADEO COMPASS L 00 CUNS'ERUCTZGN Frederick D. Herbert, .Jr., Cedar Grove, N. 5., assignor to Kearfott Engineering 00., Inc, a

corporation of New York Application August 24, 1939, Serial No. 291,762

4 Claims.

This invention relates to radio compass loop mountings and more particularly to such mountings used on aircraft in Zeppelin or tear-drop type of loop housing.

This device is designed to pick up the energy in waves propagated by radio stations and by changes in the response of the loop at the various angles between its plane and that of the propagated waves, to give an indication of the relative direction of the transmitting radio station.

It is an object of the invention to provide an improved radio compass loop assembly characterized by simplicity of construction, practicability, and economy of manufacture and assembly.

Another object is the provision of a radio compass loop mounting particularly adapted to be made from a die-casting and with a minimum of machining.

Another object of the invention is the provision of a radio compass loop mounting so adapted as to permit of the determination and correction of the electrical characteristics of the loop during a stage of its assembly.

Other objects and advantages of the invention will appear from the following description of one embodiment thereof.

In accordance with the present invention there is provided a radio compass loop mounting composed of a channel frame in the form of a circle, near the bottom of which channel are provided shoulders for holding a flat strip of insulating material bent to conform with the frame and secured thereto by screws or other conventional means. Upon this strip in its mounted position is wound the loop, with the ends thereof left long enough to reach to the base of the mounting for connection with terminals leading to the radio receiving circuits.

At this point in the assembly, electrical measurements may be made to determine the electrical characteristics of the loop in its mounted position. As the purchasers of radio compass loop assemblies hold the manufacturer to extremely narrow limits in the electrical characteristics, this feature of the invention becomes important as the electric characteristics of a loop in its assembled position may be determined and brought to the required standard before the assembly has been completed, thus saving the time and effort required to make adjustments after the assembly has been completed and found not within the standards set.

The channel of the frame is closed by two strips of metal slid into grooves machined in the inner faces of the side walls of the frame, the ends of which strips are cut away to provide a passageway for the ends of the loop.

Lugs are cast integrally with the frame for securing it to a base. A short section of the channel frame is out out at a point opposite these lugs, to prevent the frame from acting as a closed loop conductor and thus shielding the compass loop.

In the accompanying drawing:

Fig, 1 is a fragmentary cross-section of an embodiment of the invention with the base shown partly in elevation; and

Fig. 2 is a cross-section of the frame, loop and mounting on line 2--2 of Fig. 1. e As will be seen from the drawing, and more particularly in Fig. 2, the radio compass loop assembly comprises a die-cast channel frame 3, which is circular in form. The two side walls of the channel frame are provided with two opposing internal shoulders 4 adapted to receive a flat strip 5 of insulating material which is bent to conform to the shoulders 4 and is secured in position in the frame 3 by a screw 6. The strip 5 is grooved in any conventional manner on its outer face to receive the loops of wire 7 whose two ends 3 and t are the electrical terminals of the loop.

The support for frame 3 is provided by having cast integral with it the lugs Ill which are adapted to fit over a hollow shaft H and which are secured thereto by bolts [2 and nuts I 3. The shaft H is mounted in a frame and may be mounted to rotate therein or be fixed thereto in any conventional manner.

The frame 3, directly opposite the lugs it, has a short section cut therefrom so that the frame 3 does not form a closed cover for and shield the loop 1, thereby preventing it from functioning as a radio compass loop. The removal of this section also provides an easy access for sliding in the outer cover strips l5, as will be described later. This gap in frame 3 is covered with any suitable insulator 22.

To cover the open channel there are provided two strips l5 of some flexible material such as sheet aluminum which are slid in the groove I6, machined in the frame 3. The ends of these strips !5 where they meet at the bottom of the frame have each a semicircular cut-out to provide a passageway for the terminals 8 and 9 of the loop 1. These strips are of such length that when in their secured position, their upper ends are separated substantially the width of the cutout section of the frame. The outer edges 11 of the frame may be rolled over after the strips l are in place, providing a more secure fastening of the strips in position and making a tighter joint between the strips and the frame.

It will be particularly noted that when the strip 5 is secured in place in the frame 3 it is completely exposed and is accessible all the way around the frame 3. The loop 1 may then be wound on strip 5 in its assembled position. Also, because the frame is still open and accessible, the electrical characteristics of the loop in its assembled position may be measured and adjusted. This is a decided advantage in radio compass loop construction especially where the electrical characteristics of the loops are held to narrow variation.

A Zeppelin or tear-drop housing may be mounted over the loop assembly, such as shown in Fig. 1, where a shell [8 is secured to the base 19 by any conventional means such as screws 20 and plate 2|.

It is obvious that the term circular is not used herein in any strict or limiting sense and that various modifications may be made in the construction shown in the drawing and above particularly described within the principle and scope of my invention.

I claim:

1. A radio compass loop mounting comprising an open channel circular frame a section of which is removed, the said frame having circumferential shoulders on the inner portions of the interior walls of the frame and extending laterally toward the center plane of the frame and circumferential grooves in the outer portions of the interior walls of the frame, a flat strip of insulating material secured against said shoulders, .a .conducting wire wound on said strip, cover strips in said grooves, and insulating means extending across the ends of said frame at the said removed section.

2. A radio compass loop mounting comprising an open channel circular frame a section of which is removed, the said frame having circumferential shoulders on the inner portions of the interior walls of the frame and extending laterally towards the center plane of the frame and circumferential grooves in the outer portions of the interior walls of the frame, a flat strip of insulating material secured against said shoulders, a conducting wire wound on said strip, cover strips in said grooves, insulating means extending across the ends of said frame at the said removed section, lugs secured to said frame, and a hollow base secured to said lugs adapted to form a support for said frame and a passageway for the ends of said conducting wire.

3. A radio compass loop mounting comprising an open channel circular frame a section of which is removed, the said frame having circumferential shoulders on the inner portions of the interior walls of the frame and extending laterally toward the center plane of the frame and circumferential grooves in the outer portions of the interior walls of the frame, a flat strip of insulating material secured against said shoulders, a conducting wire wound on said strip, cover strips in said grooves, insulating means extending across the ends of said frame at the said removed section, lugs secured to said frame opposite the said removed section, and a hollow base secured to said lugs adapted to form a support for said frame and a passageway for the ends of said conducting wire.

4. A radio compass loop mounting comprising a circular frame of channel shape in cross section, the said frame having a section removed therefrom, circumferential shoulders on the interior side walls of said frame, a strip of insulating material secured on said shoulders, a conducting wire wound on the outer surface of said strip, circumferential cover strips secured to the frame outside the said strip, insulating means extending across the removed section of said frame, and a hollow base secured to said frame adapted to form a support therefor and to form a passageway for the ends of said conducting wire.

FREDERICK D. HERBERT, J R. 

